Myocarditis is the medical term for heart muscle inflammation. These can have different causes and can be acute or chronic. Only the heart muscle can be affected by the inflammation or even the pericardium (pericardium).
Consequence of the inflammation is a limited efficiency of the heart muscle and in the consequence a Herzschwäche (heart insufficiency). Myocarditis carries the risk of dangerous cardiac arrhythmias and sudden cardiac death, even in younger people without pre-existing conditions.